The present invention relates to the use of activated carbon to remove metallic impurities from titanium tetrachloride solutions.
The production of TiCl.sub.4 from titaniferous ores, such as ilmenite and rutile ores, utilizes chlorine gas and coke in a fluidized bed. An anhydrous TiCl.sub.4 is obtained by removal of solid and soluble impurities by treatment with oils, followed by distillation. This anhydrous TiCl.sub.4 is suitable for regular production of titanium dioxide pigments.
However, this anhydrous TiCl.sub.4 is not suitable for use in other applications such as pearlescent pigment production and in cosmetics because of small but significant amounts of toxic metals such as arsenic and antimony which are not removed by standard processing techniques.
The use of activated carbon in connection with the manufacture of titanium dioxide pigments from acid and water-soluble sulfates is known. U.S. Pat. No. 3,761,298 discloses the use of activated carbon to clarify a titanium sulfate solution. This patent does not disclose, however, the use of activated carbon in connection with the production of titanium tetrachloride, nor is there any recognition of the usefulness of activated carbon to remove specifically arsenic and antimony.